1. Field
The invention relates to a system and method of constructing wall panels for use generally in the construction industry, and can be used in individual housing construction to make wall panels for exterior and interior walls as well as for ceiling coverings.
2. Description of Related Art
Wood can be used to construct almost any part of a home from the roofing and exterior walls to the floor and interior architectural elements as well as basic domestic items like furniture and cabinets. However, in recent years the cost of solid timber wood has increased dramatically as its supply shrinks due to the gradual depletion of old-growth and virgin forests. Indeed, it is particularly expensive to manufacture solid hardwood furniture and architectural features from such material because typically less than half of harvested timber wood is converted to natural solid wood lumber, the remainder being discarded as scrap. In the building context, wood panels may be too small to cover large wall areas and wooden structures composed of multiple smaller, mass produced, timber components are desirable.
Compared to solid wood panels, such assembled wood panels have advantages. For example, assembled wood panels can be produced having a desired surface area that is not limited by the diameter of the trunk of a tree. Basically, any limitations with regard to the size of the surface area of the composite panel arise only from problems in handling the panels. Furthermore, assembled wood panels demonstrate superior strength properties compared to normal solid wood boards that are not glued because, by transverse gluing of the boards, the direction-dependent strength properties of wood can be partially compensated and, as a result, changes of board shape due to the influence of environmental factors, like moisture, can be kept within prescribed limits.
While useful for at least these reasons, typical assembled wood panels have their own deficiencies. RU 59096 provides wood sandwich panels for construction of holiday cottages. The panels contain a supporting framework made of timber with more attractive facing on an external surface and an internal surface. The supporting framework consists of inner and outer rectangular frames of equal external dimension, where one of the timbers of the long side of the frame is wider than the timbers of the other sides. The frames are mutually offset by width and are joined into one piece, forming projections for joining to other panels. The external frame has a load-bearing element mounted along its length, while the internal frame has at least three load-bearing elements mounted along its width. These load-bearing elements are typically made of timbers whose ends are attached to the frames. Due to the method of joining the various layers, additional layers of thermal insulation, waterproofing materials, and a vapor barrier are required. There is a layer of waterproofing between the inner frame and inner facing, and a vapor barrier between the outer frame and outer facing. The space between them is filled with thermal insulation. Facing is typically fabricated of wood tile and the projections for joining to other panels are covered with foamed polyethylene strip sealant.
Among the disadvantages of sandwich panels currently in use is poor air permeability caused by the presence of waterproofing and the vapor barrier. This requires supplemental humidity control within the premises of a building, because the humidity in houses with poor ventilation is always higher than in houses with normal and natural ventilation. This makes dampness, mold and rot more likely in wooden house elements, and may adversely impact inhabitant health. In addition, panels currently in use are characterized by thermal lag, inherent to the panel design, owing to the low thermal capacity of the minerals used in the basic framework volume (principally, the mineral batting). Such minerals insulate the premises from loss of heat in cold months, but in summer they are unable to relieve the house of heat.
Wood and metal composite panels such as described in RU 2354788 also are currently in use, which contain a cellular wood-and-metal framework formed by longitudinal and transverse wood boards that are joined using U-shaped metal frames that repeat their configuration and grip the boards by both sides. Stiffeners in the form of flat plates are attached to the frames at framework cell joints. The panel contains facing and a layer of waterproofed thermal insulation as well. This wood-and-metal composite panel also exhibits the aforementioned disadvantages, which are caused by the layer of waterproofed thermal insulation.
RU 2198271 describes another framing structure that contains at least three bonded layers of wood components mounted alongside each other and fabricated in the shape of boards or bars. The wood components of at least two layers are oriented in different directions. Separate layers are joined using pegs that penetrate the wood component layers. Such a design eliminates some of the aforesaid disadvantages of prior art panels. At the same time, such prefabricated units have shortcomings of their own. One of these concerns the fact that pegs completely penetrate the prefabricated unit, thus resulting in a need to apply additional finishing material. Such prefabricated unit also tend to exhibit higher air permeability. In addition, in use, such prefabricated panels are prone to structural loosening.